Automatic yarn tension control



Jan. 13, 1953 P. J. SCHOENSTE-ZR EI'AL 2,625,021

AUTOMATIC YARN TENSION CONTROL Filed Feb. 1, 1949 s Sheets-Sheet 1 W1 TNESSES I N VE N TOR S.

Wild, BY flfTORNEYS.

Jan, 113, 1953 P. J. SQCHOENSTER "El-A1. 2,625,621 AUTOMATIC YARN TENSION CONTROL 3 Sheets-Sheet 2 Filed. Feb. 1, 1949 www [3622, By Maxi E ATTORNEYS.

Jan. 13, 3953 P. J. SCHOENSTER ETAL ,5

I AUTOMATIC YARN TENSION CONTROL Filed Feb. 1, 19 .9 3 Sheets-Sheet 5 W1 TN ESSES I N V EN TOR S I l -5 i 4f%1% 5555 5'22??? 1 A'ITORNEYS.

Patented Jan. 13, 1953 AUTOMATIC YARN TENSION CONTROL Peter J. Schoenster, Teaneck, and Max E. Ebert,

West New York, N. J assignors to Alfred Hofmann & 00., West New York, N. 1., a corporation of New Jersey Application February 1, 1949, Serial No. 74,002

13 Claims.

This invention relates to automatic yarn tension control mechanism useful in connection with textile machines such, for example, as warp knitting machines of the Tricot or Raschel types wherein the warp yarns are drawn from a supply beam on route to the knitting needles.

The chief aim of our invention is to make it possible to produce, in machines of the kind referred to, fabrics which are free of shadow lines, streaks and other imperfections occasioned by irregularities in stitch size due to variations of the tension imposed on the yarns during the knitting.

This objective is realized in practice, as hereinafter more fully disclosed, through provision of a relatively simple and reliable tension control mechanism capable of ready incorporation in existent textile machines without entailing any structural changes in them or requiring any modification in their usual mode of operation, and capable moreover, of maintaining a uniform predetermined tension on the yarns at all times. Briefly stated, this improved control mechanism includes a pair of shafts one of which is geared to the warp beam, and the other of which is norinally free and constantly driven; electro-magnetic braking and clutching means normally energized and balanced against each other; a detector adapted to be influenced by the yarns as they come from the beam; and means actuated by the detector for decreasing current flow to the clutch means so that the geared shaft is momentarily restrained and the beam held against rotation in the event of slacking of the yarns, and

for increasing current flow to the clutching means so that the two shafts momentarily coupled for impartation of a slight forward rotary feed movement to the beam in the event of any tendency of the yarns to tighten.

Other objects and attendant advantages will appear from the following detailed description of the attached drawings, wherein:

Fig. 1 is a fragmentary view in elevation of a portion of a textile machine with an automatic yarn tension control mechanism conveniently embodying our invention.

Fig. 2 is a fragmentary view in end elevation looking from the right of Fig. 1.

Fig. 3 is a fragmentary view in longitudinal section showing the magnetic clutching and braking means of the mechanism; and

Fig. 4 is a diagram showing the wiring connec tions of the mechanism.

In Fig. 1 there is indicated for the purpose of exemplification, the rotary .beam B of a warp ail) knitting machine from which the yarns W are drawn, on route to the knitting instrumentalities (not shown), in a well known way incident to the formation of knitted fabric.

The automatic yarn tension control mechanism with which the present invention is more particularly concerned is comprehensively designated It. As seen to the best advantage in Figs. 2 and 3, it comprises a horizontally-arranged tubular shaft II which, in practice, is fashioned from non-magnetic material such as brass or the lik and which is rotatively supported in a bearing sleeve i2 secured by screws l3 to a plate 14 likewise of non-magnetic metal. This plate I4 is in turn secured to an outboard bracket l5, also of non-magnetic material, aflixed to the side frame F of the machine by screws l6. Keyed or otherwise fastened to the inner end of the tubular shaft II is a spur pinion ll that meshes with a spur wheel 18 on the shaft of warp beam B. Independently rotative within the tubular shaft II is an axial shaft l9 whereto is affixed, at one of its protruding ends, a sprocket pinion 20 which, through a chain 2|, is constantly driven from a sprocket pinion 22 on the power shaft S of the knitting machine. Fastened to the bearing sleeve I 2, by set screws E i, is the core spool 25 for the coil 26 of a magnetic fluid brake; and similarly secured, by set screws 21, to the outer end of shaft l9 beyond the tubular shaft II is the core spool 28 for the coil 29 of a magnetic fluid clutch. As shown, the magnet coils 26 and 29 respectively are surrounded, with interposition of circumferential clearances at 36 and 3|, by tubular housings 32 and 33 of iron or other magnetic material, said housings having peripheral flanges 32a and 33a at their contiguous ends secured, by screws 35 and 36, to a terminal flange Ha at the outer end of the tubular shaft H so as to be bodily rotative with the latter. In practice, the brake and clutch housings 32 and 33 are filled with oil or grease in which iron powder or other comminuted magnetic material is sus pended. The distal end of the housing 32 abuts the plate It, while the distal end of housing 33 is closed by a cover plate 37. The ball bearings indicated at 38, 39 and 40 ease rotation of the housings 32 and 33 about the shafts II and I9 respectively. Electric current is conducted to th brake magnet coil 26 by way of conductors El and 42 threaded through communicating passages in the sleeve [2 and in the plate l4. Current leads s5 and 46 extend from the clutch magnet coil 29 to rings 41 and 48 embedded in collars 49 and 5B of insulation, said collars being 3 secured to the outer end of the shaft [9 and held in place thereon by a screw attached cap 5|. Bearing against the rings 41 and 48 are spring pressed brushes 52 and 53 which are lodged in guide bores of a block 54 of insulation afixed to the outer end of bracket [5. Electric current is carried to the brushes 52 and 53 by conductors 55 and 56 also threaded through the hollow of bracket [5. Flow of current to the magnetic clutch coil 29 is governed by a, detector element in the form of a finger 60 (Fig. 1) which is fulcrumed on a stud Bl extending inward from the side frame F of the machine, and which, at its swinging end, has a lateral stud projection 62 bearing against several of the warp yarns W as they leave the beam B. Through a link rod 63, the finger 60 is connected to the actuating arm 65 of a rotary rheostat 66.

As shown in diagrammatic Fig. 4, the current carrying conductors 4| and 42 for the brake magnet coil 26 are connected across the secondary coil 61 of an alternating current transformer 68, and interposed in the conductor 4| is an adjustable, resistance 69. The current leads from the ring brushes 52, 53 are similarly connected across the secondary coil of transformer 68, with interposition of the rheostat 65 in conductor 52, and an adjustable resistance 10 in conductor 55. By opening the hand switch indicated at 1 I, the electrical system may be rendered dormant upon stopping the machine.

Operation Normally, with the resistances 69 and 10 properly adjusted and the movable contact 13 (Fig. 4) on the center of the coil 12 of rheostat $6, the electrical system is in perfect balance. Under these conditions the tubular shaft H and the housings 32 and 33 secured thereto are idly turned slowly through the gears I! and [8 from the warp beam B. In the event of any tendency of the warp yarns to slacken, the detector finger 62 will drop slightly and shift the movable contact 13 of rheostat 66 in one direction to reduce current flow through the clutch coil 29, with the result that tubular shaft II and the beam B are restrained momentarily by the action of the brake magnet 28 until the normal yarn tension is reestablished. On the other hand, in the event of any increases in yarn tension, the detector finger 50 will be lifted slightly and shift the movable contact 13 of rheostat in the opposite direction so that additional current will then fiow to the clutch coil 29 to overcome the action of the brake magnet 26. As a consequence, the housings 32, 33, and hence the shaft I9, will be momentarily coupled to the shaft II with impartation of slight positive rotary feed movement to the warp beam B until the strain on the yarns is relieved and the normal tension is reestablished. Accordingly, by' this automatic compensative action, it will be apparent that the tension on the yarns will be kept uniform at all times and the loops of the fabric held to a definite size throughout the knitting, with resultant production, by the machine, of fabric which is devoid of lines, streaks or other imperfections.

Having thus described our invention, claim:

1. Automatic yarn tension control mechanism for textile machines in which the yarns are drawn from a rotary supply beam, comprising a tubular shaft gear connected to the yarn beam; a fixed bearing for said shaft; a constantly driven shaft normally free within the tubular shaft; energized brake and clutch electro-magnets respectively mounted on the bearing for the tubular shaft and on a protruding end of the axial shaft, and normally energized so as to be balanced against each other; housings secured to a fiange on the tubular shaft and surrounding the brake and clutch magnet, with interposition of circumferential clearances, and containing fluent magnetic media; a detector adapted to be influenced by the yarns as they leave the beam; and means actuated by the detector to decrease the supply electric current to the clutch magnet upon slacking of the yarns, and to increase the current supply to the clutch magnet upon tightening of the yarns.

2. In automatic mechanism for controlling the tension of textile material or the like en route to or from a beam, a constantly driven shaft; a coaxial shaft through which the beam is rotated; electro-magnets normally energized to the same degree, one stationarily supported and encircling one of the shafts, and another afiixed to the shaft; a surrounding member of magnetic material revolved with said one shaft and serving as a common armature to react with the two magnets; a detector adapted to be influenced by the material en route to or from the beam; and regulating means actuated by the detector for decreasing the supply of electric current to one of the magnets upon slacking of the material, and for increasing the current supply upon tightening of the material.

3. Automatic tensioning mechanism according to claim 2, wherein the coils of the electro-' magnets are connected in a normally balanced circuit with a rheostat which constitutes the regulating means.

4. Automatic tensioning mechanism according to claim 2, wherein the surrounding member is in the form of a closed housing containing mag netic fluid.

5. Automatic tensioning mechanism according to claim 2, wherein the surrounding member is in the form of a closed housing with separate subdivisions for the respective magnets containing magnetic fluid.

6. In automatic mechanism for controlling the tension of textile material or the like en route from or to a beam; a tubular shaft through which the beam is rotated; a constantly driven shaft axially within and having one end thereof protruding beyond the tubular shaft; electromagnets normally energized to the same degree, one stationarily supported and encircling the tubular shaft and the other fixed upon the protruding end of the axial shaft; a surrounding member of magnetic material secured to the tubular shaft and serving as a common armature to react with the coils of the two magnets; a detector adapted to be influenced by the material en route to or from the beam; and means actuated by the detector to decrease the current supply to one of the magnets upon slackening of the yarns, and to increase the. supply of current to such magnet upon tightening of the material.

'7. Automatic tensioning mechanism according to claim 6, wherein the tubular shaft is of nonmagnetic material and rotatively supported in a non-magnetic bearing.

8. Automatic tensioning mechanism according to claim 6, wherein the surrounding member is in the form of a closed housing containing magn t e u d-j 9. Automatic tensioning mechanism according to claim 6, wherein the surrounding member is in the form of a closed housing with separate subdivisions for the two magnets containing magnetie fluid.

10. In beam driving mechanism for textile machines or the like, a two section shaft, one operatively connected to the beam and the other power driven; a magnetic slip clutch including a coil component aflixed to one shaft section, an armature component affixed to the other shaft section, and loose particles of magnetizable material contained in a spacial interval between said components; and means automatically operative to vary current supply to the magnet coil compensatively with tension variations in the material being Wound upon or unwound from the beam for maintenance of the material under uniform tension.

11. In beam driving mechanism for textile machines or the like, a two section shaft, one operatively connected to the beam and the other power driven; a magnetic slip clutch including a coil component affixed to one shaft section, an armature component amxed to the other shaft section and loose particles of magnetizable material contained in a spacial interval between said components; a detector adapted to be influenced by the material en route to or from the beam; and regulating means automatically actuated by the detector to increase current supply to the magnet coil upon slackening of the material, and to decrease the current supply to said coil upon tightening of the material for maintenance of the latter under uniform tension.

12. In beam driving mechanism for textile machines or the like, including a two section shaft, one operatively connected to the beam, and the other power driven; a magnetic slip clutch and a magnetic brake, said clutch and said brake each including a coil component affixed to one shaft section, an armature affixed to the other shaft section, and loose particles of magnetizable material interposed between said components; and control means automatically operative to vary the current supply as between the coils of the clutch and brake compensatively with tension variations in the material being wound upon or unwound from the beam, for maintenance of the material under uniform tension.

13. In beam driving mechanism for textile machines or the like including a two section shaft, one operatively connected to the beam, and the other power driven; a magnetic slip clutch and a magnetic brake, said clutch and said brake each including a coil component affixed to one shaft section; an armature affixed to the other shaft section, and loose particles of magnetizable material interposed between said components; a detector adapted to be influenced by the material en route to or from the beam; and regulating means automatically actuated by the detector to increase the current supply to clutch magnet coil and to decrease the current supply to the brake magnet coil upon slackening of the material, and vice versa upon tightening of the material, for maintenance of the latter under uniform tension.

PETER J. SCHOENSTER. MAX E. EBERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,155,124 Berger Sept. 28, 1915 2,470,125 Young May 17, 1949 2,486,525 Fuhrer Nov. 1, 1949 OTHER REFERENCES Nat. Bu. Standards Technical Report 1213, page 8, Figs. 5-10, Mar. 30, 1948. 

